With a recent increase in network traffic, a network that implements a connection between points with a large capacity is needed. Especially, when an enterprise network is configured, a one-to-multi network connection (multipoint connection) such as a connection between a data center and a plurality of points is important.
FIGS. 1A and 1B are explanatory views of a conventional technique.
As a technique for connecting between points with a large capacity, a connection using an ODU (Optical channel Data Unit) defined by ITU-T Recommendation G.709 is effective. However, when a one-to-multi network connection (multipoint connection) for individually deciding bands for points is made, the connection needs to be made by setting a plurality of point-to-point (p2p) ODUs as illustrated in FIG. 1A. In this case, it is needed not only to individually manage the ODUs but to uniquely set routes. Accordingly, there is a possibility that paths of a plurality of routes are set for a partial area within a network.
A case where a network apparatus X and network apparatuses Y and Z are respectively connected as illustrated in FIG. 1A is considered as an example. Assume that there are nodes A to E as relay nodes. If a service operator requests setting of a path (2) after optimally setting a path (1), a network operator sometimes provides a route A-B-D-C due to an insufficient bandwidth between the nodes A and C. However, when communications using the routes (1) and (2) are set, both of the routes (1) and (2) can be sometimes set by using a route A-B-D-C-E. As a result, the number of links (also the number of nodes depending on a case) to be managed as a whole in the case of FIG. 1B becomes smaller. Therefore, it is more efficient in operations for both of the routes to set a route by aggregating routes as many as possible when routes are set from one point to multi points. Here, a path is a communication route used for a communication between points, and includes a plurality of relay nodes. In contrast, a link is a physical connection route between nodes.
Namely, in the case of FIG. 1A, the route (1) between X and Y is optimally formed, and the route (2) between X and Z is formed next. However, since the bandwidth between A and C is insufficient on the route of (2), the route A-B-D-C is formed via the nodes B and D. Here, in FIG. 1B, the nodes A to E are collectively set on the routes (1) and (2). In FIG. 1A, the number of links is 5 (A to E, A to B, B to D, D to C and C to E) and the number of ports is 10. In the meantime, in FIG. 1B, the number of links is 4 (A to B, B to D, D to C and C to E) and the number of ports is 8. Accordingly, it is proved that the number of inks and the number of ports, which are to be managed, are smaller in the case of FIG. 1B.
FIG. 2 is a block diagram illustrating a configuration of a conventional relay node.
An input optical signal is input to an Och/OTU HO ODU (Optical ch/Optical channel Transport Unit/High Order channel Optical Data Unit) processing unit 10. The Och/OTU HO ODU processing unit 10 processes an overhead of an outer frame (HO ODU) in a layered frame that configures the optical signal, and extracts contents of a payload. LO ODUs (Low Order Optical channel Data Units) extracted from the payload of the HO ODU are individually input to prepared LO ODU processing units 11-1 to 11-3. After storing the received LD ODU in a buffer and extracting a clock, the LO ODU processing units 11-1 to 11-3 input the LO ODU and the clock to SW internal processing units 12-1, 12-2. The SW (SWitch) internal processing units 12-1, 12-2 store the LO ODU in a buffer, extract an OPU (Optical channel Payload Unit) from a payload of the LO ODU, generate an internal frame that is a unit of switching used within a switch (SW) 13, and output the generated frame to the switch 13. This OPU extraction process corresponds to a TS (Tributary Slot) process.
The internal frame for which a switching process has been executed by the switch 13 is input to SW internal processing units 15-1, 15-2, which reconfigure an LO OPU from the internal frame. Then, LO ODU processing units 16-1, 162 insert an overhead and the like in the reconfigured LO OPU, and input the LO OPU to HO ODU processing units 17-1, 17-2. The HO ODU processing units 17-1, 17-2 store the received LO ODU in a payload of HO ODU, generate an overhead, and assemble and transmit the HO ODU. A system clock 14 supplies an operation clock to the SW internal processing units 12-1, 12-2, 15-1, 15-2 and the switch 13.
Examples of conventional techniques include a technique for forming a dedicated channel between electronic edge switches of edge nodes, a technique for setting an optimum end-to-end path, a technique for setting an efficient path independently of a traffic pattern, and a technique for extracting information of a route having a minimum cost in advance.